Portable refrigerant recovery units or carts are used in connection with the service and maintenance of refrigeration systems, such as a vehicle's air conditioning system. The refrigerant recovery unit connects to the air conditioning system of the vehicle to recover refrigerant out of the system, separate out oil and contaminants from the refrigerant in order to recycle the refrigerant, and recharge the system with additional refrigerant.
Due to the phase changing nature of refrigerant, as refrigerant is removed from the vehicle's air conditioning system or other such refrigeration systems, the pressure decreases which causes the refrigerant to vaporize. As this refrigerant vapor is removed, the heat of vaporization is removed from the air conditioning system causing the air conditioning system to become colder. As the temperature of the air conditioning system decreases, the refrigerant remaining therein may be chilled below its boiling point, which makes the liquid refrigerant difficult to completely remove.
Accordingly, it is desirable to provide a method and apparatus capable of overcoming the disadvantages described herein at least to some extent.